<div style="width: 100px; height: 100px; background-color: red;"></div>
<div style="
    margin-top: -100px;
    background-color: red;
    border-radius: 50px;
    width: 80px;
    height: 80px;
    border-width: 10px;
    border-color: rgba(0, 0, 255, 0.5);
    -webkit-border-image: linear-gradient(green, green) 10 10 10 10;
    border-style: solid;
"></div>
